The invention relates to a fixing member for use with setting materials, in particular an anchor bolt securable in a blind borehole in concrete using an injection resin mortar.
To anchor a load on the external surface of a fixed structural component such as reinforced concrete, fixing members are conventionally used that are inserted into blind boreholes and engage the structural component creating an interlocking and frictional connection therewith. The fixing member are sometimes fastened adhesively using a setting material between the fixing members and the wall of the borehole, whereby the setting material is injected either prior to introduction of the fixing member by using a destructible tubular bag or by way of injection ports or openings after introduction of the fixation means, whereby mainly excess material overflows the annular space. The fixing member situated loosely in the borehole must be fixed in its position and cannot be mechanically stressed until the material sets, which, for example, in the case of a ceiling assembly, requires additional support of the dead weight. On the other hand, in the case of elevated ambient temperatures and the consequently faster reaction time the fixing member that must be introduced into the borehole immediately after the onset of the reaction can generally no longer be re-adjusted. Such method steps that necessarily follow upon one another represent a significant coordination problem particularly in carrying out complex construction projects.
The fixing member subjected to traction and shearing forces are generally designed as anchor or anchors bolts. In the case of the anchor a threaded bolt protruding above the external surface serves in the attachment of assembly components. The anchor bolt that functions as an anchor with displacement controlled expansion for the connection of two surfaces is designed with external ribs for the purpose of interlocking embodiment as an extension of the reinforcement of concrete subsequently poured around it. Anchor bolts are a very inexpensive mass-produced product that are generally manufactured as an elongated product that is cut to length as needed.
U.S. Pat. No. 5,466,086 discloses a fixing member provided with an axial passage running through it and having radial ribs that advantageously form an alternating changeover between set material and the fixing member along its axial plane in direct contact with the opposing surface of the borehole wall, the alternating contact being advantageous in stopping cracks. DE4033396 discloses a sleeve-like assembly element for the fixing member designed as an anchor bolt having radial recesses, and ribs axially running so centering the anchor bolt coaxially, that being embedded in the setting material also act as crack stoppers. DE431594 discloses anchor bolts wherein the crack stop is realized using non-adhesive longitudinal webs.
According to DE19725923 the radial grooves of the anchor bolt are formed from angular indentations arranged in even intervals. According to EP0947713 the surfaces of the anchor bolt making contact with the adjacent surfaces of the borehole are in an alternating arrangement and surrounded by grooves that separate longitudinally and then again unite.
Further, DE4206260 discloses a device for rotary swaging/kneading of metal tubes.
The object of the invention involves a fixing member that is uncomplicated and can be mass produced, the fixing member being used with setting materials, in particular an anchor bolt for use wit injection resin mortar. A further object involves the capability of pre-positioning and pre-stressing the fixing member prior to its being adhesively bonded and in the time interruption of the process steps.
Essentially a fixing member, advantageously designed as an anchor bolt of the type of an injection anchor with displacement controlled expansion, a so-called dowel, using a setting material in a blind borehole is anchored in concrete, formed as a peripherally closed medium or thick-walled tube of uniform wall thickness with an axial passage running through it, which is radially at least partially indented or deformed.
Peripherally closed tubes of uniform wall thickness are available as semi-finished tubular goods and are easily cut locally to the appropriate, required length. The initially fluid setting material can easily be injected through the axial passage in the already positioned fixing member into the bottom of the blind borehole and externally into the annular space formed with the inside wall of the blind borehole. The deformations in the anchor bolt form, on the insertion section, radial recesses with respect to the inside wall of the borehole, which form a interlocking axial connection after the material hardens or sets, for example, a reaction resin mortar. In the cross-section of the tubular member, while maintaining the peripheral length of the neutral chord by the deformation, protuberances are formed at other peripheral locations which, depending on the shape of the protuberance, extend beyond the original diameter.
The minimal reduction of the tensile strength by the medium- to thick-walled circular ring surface versus the cylindrical area of the round profiles (xe2x80x9croundsxe2x80x9d) is acceptable or, with the same weight of the fixing member, compensable by the use of a larger diameter of the fixing member. The area moment determining the flexural resistance for transmission of the shearing forces is comparable in tubes with that of round profiles. By the uniform wall thickness, the force inducted into the fixing member inside of the borehole, in particular even with dynamic loading, can be transferred without locally significant deformations or damage in the fixing member.
The local protuberances at the margin of the indentations extend advantageously at least partially beyond a coaxial diameter, which is slightly larger than that of the undeformed tubular member or that of the associated blind borehole, whereby the fixing member can be centered by said local protuberances coaxially in the associated blind borehole and can be subsequently mechanically positioned and re-adjusted with respect to minor loads. The injection of the adhesive setting material through the axial passageway in the tubular member can be done at any later time prior to stressing with the nominal loading.
The advantageous alternating changeover between setting material and direct contact with the wall of the borehole along the axial plane forms a crack stop in the form of an axially limited length for any crack proliferating along the interface boundary between the setting material and the fixing member.
The deformed partial areas of the tubular member advantageously form even flat or planar areas, whereby a strain-resistant stiffening of the sectional area of the fixing member is created.
The deformed regions are advantageously arranged at least in part alternating along the axial region of the fixing member, whereby the deformed regions are further advantageously half-angularly displaced; thus, in the case of two opposing deformed regions at 90xc2x0 or in the case of indentations forming an equilateral triangle 60xc2x0.
Along the deformed regions, grooves are formed advantageously extending along the length of the fixing member, which diverge longitudinally in the preferably circular-round transition areas or converge again, whereby the peripherally uniform distribution of the setting material exiting at the base of the borehole is achieved.
The fixing member is advantageously manufactured of cold-worked steel using the rotary swaging/kneading process, whereby the structural fabric is not damaged by cutting work and its strength is increased compared to hot-working. In particular, the rotary swaging/kneading process is applicable to tubular material available as a tubular semi-finished product, whereby the fixing member can be pre-fabricated at least in part continuously from tubular material and the axially periodic deformed regions and protuberances can be cut to length at the site.
The fixing members being cut to the desired length for tranmission of forces are designed as anchor bolts in an initial preferred variation, which are introduced into a blind borehole with half the length of the overall length of approximately 20 times the diameter and further advantageously mechanically positioned. The anchor bolt is bonded with the solid body interlocking adhesively by using injection mortar.
In an expedient application of the anchor bolt as an anchor with displacement controlled expansion, a hole made previously in another solid body, previously or subsequently filled with a initially fluid setting material, is positioned at the free end of the anchor bolt, whereby after setting of the setting material both bodies are adhesively bonded interlocking with each other.
In a preferred embodiment of the anchor, an inner or outer screw thread is applied to the rounded end of a cut-to-length fixing member before or after it is secured in the solid body.